1. Field of the Invention
The present invention relates to a camera which uses a film provided with a magnetic storage section in which data can be written or from which data is read.
2. Description of the Related Art
In conventional film feeders of cameras, a film is loaded in a camera by driving a sprocket or a film winding spool of the camera in the state wherein the tip-end (so-called leader portion) of the film projected from a film cartridge is engaged with the sprocket or the film winding spool of the camera. However, this type of film feeder has the fault that the user must perform the troublesome operation of setting the tip-end of a film, and if the film tip-end is placed at a wrong position, the film is loaded wrong. The film feeder also has the fault that if the film tip-end is carelessly pulled, the film is made unusable due to an unwanted exposure.
Thus U.S. Pat. No. 4,834,306 has recently proposed a new type of film cartridge that includes the following:
A film cartridge comprising a film passing slit, a film which has an end fixed to a supply spool and which is wound on the supply spool, a pressure member which is coaxially disposed on the supply spool and which has a regulation section for regulating the radial expansion of the film winding so as to prevent the outermost periphery of the film winding from substantially contacting with the innner wall of the film cartridge, a release section for partially deforming the pressure member so as to continuously release the outermost periphery of the film winding from the radial regulation by the pressure member, and a guide section for guiding the portion of the film which is released from the regulation to the film passing slit. The film winding is outwardly expanded due to the loosening of the film caused by the rotation of the supply spool in the direction of film push-out so that the pressure member does not slip on the outer periphery of the film winding, whereby the film can be pushed out of the film cartridge by applying driving force to the film in the direction of push-out. This type of film cartridge in which the film can be discharged by rotation of the supply spool is referred to as "push-out type film cartridge" hereinafter.
FIGS. 24 to 26 show such a push-out type film cartridge, in which FIG. 24 is a longitudinally sectional view, FIG. 25 is a cross-sectional view and FIG. 26 is a side view of a principal portion.
In the drawings, reference numeral 301 denotes a film; reference numeral 302, a push-out type film cartridge; reference numeral 303, a film passing slit; reference numeral 304, a supply spool; reference numeral 304a, a fixing section for fixing one end of the film 301; reference numeral 305, a pressure member; reference numeral 305a, a regulation section; reference numeral 306, a release section; and reference numeral 307, a guide section.
The use of the push-out type film cartridge 302 enables the realization of a configuration in which, after the film has been loaded in a camera, the film 301 is discharged and pushed out by rotating the supply spool 304 in the cartridge 302 using a fork until the film is wound on a film winding spool of the camera, and the film 301 is then pushed out by the film winding spool. Since there is no need for the user to contact the tip-end of the film 301, this type eliminates several of the faults of conventional cartridges.
A film provided with a magnetic storage section in which data can be written or from which data can be read by using a magnetic head in synchronism with the feeding of the film has recently been proposed as a film which can be received in the above-described type of film cartridge. For example, U.S. Pat. No. 4,864,332 disclose 8 a camera in which photographic data such as a shutter time by second, a diaphragm value, a date, a title and so on are written in the magnetic storage section, and the film sensitivity and the like, which are previously written therein, are read from the storage section by using a magnetic head.
However, a camera which uses the above push-out type film cartridge has the following inconvenience:
Although the feed speed of the film is low and stable until the tip-end of the film is wound on the film take-up spool of a camera after the film has been pushed out of the cartridge, the feed speed of the film abruptly increases after the tip-end of the film has been wound on the take-up spool. This causes erroneous operation if an attempt is made to write data in or read data from the magnetic storage section of the film in synchronism with the film feeding during the film feeding operation.